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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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In general, BCF and BAF data show an inverse relationship to exposure concentrations.
BCF's for cadmium are highest in algae and lowest in fish. In algae, external adsorption of Cd is one of the reasons for high BCF. Hardness and Cd concentration in the water are inversely related to BCF.
Median BCF (per dry weight) reported in the EU risk assessment (ECB 2008) are: 115116 (algae), 5000 (invertebrates), 233 (vertebrates)
The risk assessment mentions a median BAF for vertebrates of 167. Highest BAF is observed for the invertebrate Hyalella (170000), at a very low Cd concentration.

Key value for chemical safety assessment

Additional information

Introductory note: due to the insoluble nature of the Cd-pigments, their potential for release of Cd++ in the environment is very limited. For this reason, this section has less relevancy for the Cd-pigments. It is given as general background to Cd++ toxicity.

BCF's for cadmium are highest in algae and lowest in fish; High BCF in algae does not necessarily reflect high bioconcentration, because a significant part of the Cd is absorbed to the outer side of the organisms, and not taken up. For this reason, results on algae are usually not considered in a context of BCF. Another factor of error is the lack of gut clearance in invertebrates. Organs (kidney, liver) contain most Cd.

Main influencing factors for Cd BCF are hardness and Cd concentration in the water. Increasing water hardness reduces Cd uptake. BCF is also inversely related to Cd concentration in water.

McGeer et al (2003) recently extensively the reviewed evidence on bioconcentration and bioaccumulation of cadmium as a function of exposure concentration in a number of taxonomic groups (algae, molluscs, arthropods, annelids, salmonid fish, cyprinid fish, and other fish). The data clearly illustrated that there is a significant degree of control on internal cadmium content. In general, BCF data showed an inverse relationship to exposure concentrations. In all cases, the relationship of BCF to exposure was significant and negative. The slopes of the BCF/BAF – exposure relations were: algae: -0.72, insects: -0.32, arthropods: -0.61, molluscs: -0.50, salmonids: -0.87, Centrarchids: -0.47, Killifish: -0.05, other fish: -0.72. Overall, species mean slope was -0.49 +/- 0.04 (McGeer et al 2003. Environm. Toxicology & Chemistry, vol 22, nr 5, 1017 -1037).

The following information is taken into account for any hazard / risk / bioaccumulation assessment:

In general, BCF andBAF data show an inverse relationship to exposure concentrations.

BCF's for cadmium are highest in algae and lowest in fish. In algae, external adsorption of Cd is one of the reasons for high BCF. Results on algae are usually not considered in a context of BCF.

Hardness and Cd concentration in the water are inversely related to BCF.                    

MedianrelevantBCF (per dry weight) reported inthe EU risk assessment (ECB 2007) are: 5000 (invertebrates), 233 (vertebrates)

The risk assessment mentions a median BAF for vertebrates of 167. Highest BAF is observed for the invertebrate Hyalella (170000), at a very low Cd concentration.

Considering the weight of evidence and mainly because of this well documented inverse relationship between BCF and exposure, it is concluded that Cd and its compounds are not to be considered as bioaccumulative. It has also been demonstrated that Cd is not biomagnifying in the lower parts of the foodchain.